Field of the Invention
This invention relates, in general, to the construction of chucks and, in particular, to a new and useful chuck for machine tools which includes both centering jaw heads and compensating jaw heads.
The invention relates to a chuck for lathes or similar machine tools with a compensating jaw set to be actuated through a compensating means for adaptation to irregular workpieces and with a centering jaw set to be actuated independently thereof whose jaws engage the outer faces of the workpiece in axial spacing from the compensating jaws and can be retracted out of the centering region.
A chuck of this kind is known from DE-PS No. 18 00 271. The centering jaws, on the clamping side ends of which jaws acting on the workpiece to be clamped are detachably applied, are formed by rods which slide in cylindrical bores in the chuck body. However, since the axes of these bores converge toward the clamping side end, the jaws acting on the workpiece are displaced also in the axial direction. The workpiece is thus subject to an additional, axially directed stress. This sometimes leads to an axial displacement of the workpiece so that the clamped position in not exact. Besides, the overall dimensions of this chuck design are very large in the axial and also in the radial directions due to the rod type centering jaws inclined to the longitudinal axis of the chuck. However, the clamping range is small because the radial feed of the jaws depends on the slant of the centering jaws. Another disadvantage is that for different workpiece diameters the jaws make contact at different axial distances from the clamping point of the jaw set. This complicated chuck is therefore not suitable for versatile use especially in automated clamping operations.